1. Field of the Invention
The present invention relates to a disc recognition method and apparatus, and particularly to a DVD (Digital Versatile Disc) recognition method and apparatus that recognizes DVDs as DVD-RAM or DVD-RW/DVD+RW according to the difference between tracking error signals corresponding to the inner and outer circles of the DVD respectively.
2. Description of the Related Art
Optical storage media are important in the evolution of data storage media. With the development of optical storage media, data can be recorded and backed up to high capacity, light discs, with the optical storage media taking the place of traditional data storage media. In optical storage media, DVD has significant advantages in data density and capacity compared to VCD and CD, therefore, DVD players (DVD-ROMs) are taking the place of VCD or CD players gradually and becoming essential equipment.
DVD players are compatible with VCD and CD, that is, can read VCD and CD including CD, CD-R, and CD-RW and DVD including DVD, DVD-R, DVD+RW, DVD-RW, and DVD-RAM. After the type of disc is recognized, the DVD-ROMs use an appropriate laser with a specific wavelength to read data from the disc.
In conventional disc recognition method, Taiwan Patent No. 397969 recognizes a disc according to the thickness of protection layer of the disc. For example, with the data reflection layer of CD at 1.2 mm and the data reflection layer of DVD is 0.6 mm, the disc can be recognized by detecting the thickness of protection layer of the disc. In addition, FIG. 1 shows a DVD recognition method. After the disc is recognized as a DVD, in step S11, the DVD-ROM focuses servo operation on the disc. Then, in step S12, the type of the DVD is recognized according to the magnitude of DPP (Differential Push Pull) TE (Tracking Error) signal of the disc. If the magnitude of the DPP TE signal is large (Yes in step S13), in step S14, the DVD is recognized as a DVD-RAM. If the magnitude of the DPP TE signal is small (No in step S13), in step S15, the DVD is recognized as a DVD-RW/DVD+RW.
However, since the thickness of dyestuff and quality of DVDs of respective manufacturers are different, there is no effective and accurate recognition rule provided by the above conventional method. If the recognition result is wrong, more time will be spent on another recognition process, or the DVD-ROM will fail to read the disc.